Connectors of this type use, for example, a crown nut according to German Industrial Standards, Sheets DIN 935 or DIN 937. A cotter pin type member functions as a locking element which engages the screw bolt and the nut. For this purpose the crown nut is provided with slots spaced from one another circumferentially by 60.degree. sectors. The crown nut can thus be adjusted only in 60.degree. steps. This is a disadvantage because when it is necessary to turn the nut by a full 60.degree. in order to reach the next cotter hole, it is quite possible that the bolt is exposed to an excessive strain, especially if the bolt is provided with a fine threading.
Another type of safety mechanism for preventing the loosening of a nut is known in the machine tool construction and uses a so-called safety washer having an inwardly turned nose according to German Industrial Standard DIN 462, suitable for nuts with a groove. This type of safety device is suitable for securing a nut at the end of a shaft. However, the threading of the shaft must be provided with a longitudinal groove for the nose of the safety washer. This type of construction is suitable only in machine tool construction because it is rather expensive. In bolt and nut connectors intended for use in general applications the formation of a longitudinal groove in the threading of the bolt is too expensive.
The above mentioned screw connectors provide an effective safety against losing the nut, since the nut is connected to the bolt, however, the known devices are not very effective against loosening and partial rotation of the nut relative to the threaded bolt.